There is a known method of liquid product thermal treatment intended to destroy or decrease the amount of harmful microorganisms (also referred to herein simply as microorganisms) wherein microorganisms are killed by mixing liquid product with a heating medium (e.g., sterile water steam) thereby heating the liquid product, and maintaining it at a temperature that ensures pasteurization or sterilization.
One drawback of this known method is that the liquid product mixes with water when steam condenses during the process of product cooling. This increases product mass on average by about 30% and as a result water removal is necessary. The water removal generally requires additional equipment, processing steps, time and expense. Another drawback of this known method is potential deterioration of product quality and taste after pasteurization due to destruction of vitamins and protein coagulation because of the temperature to which the product is raised.
Another known method with similar technical characteristics is one in which liquid product is mixed with a heating medium of condensing steam, and the liquid product is heated at a rate of about 1400° C./sec or more for pasteurization and about 7600° C./sec or more for sterilization to a temperature not exceeding the temperature at which qualitative changes in liquid product takes place (such qualitative changes and temperatures being known to those skilled in the art). The product is diffused into drops preferably not exceeding 0.3 mm in diameter (this process is described in Russian Patent No. 2,052,967, the disclosure of which that is not inconsistent with the disclosure herein, is incorporated by reference). This method promotes efficient thermal treatment of the liquid product, sufficiently kills microorganisms and does not adversely impact the qualitative aspects of the liquid product, because it increases the rate at which the liquid product is heated and only maintains the product at a high temperature for a short duration. The liquid product is heated only to a temperature lower than that which does not affect qualitative changes in the liquid product. This method is performed in a pasteurization device, which contains a liquid product diffuser, a pasteurization chamber, a nozzle for steam, a steam generator, a cooling chamber, and a vacuum pump.
A drawback of this method is that it does not exclude mixing of product with steam condensate, which can adversely impact the stability of organoleptic and physicochemical properties (such as taste, odor, color and consistency) of such liquid products, which include, for example, non-frozen concentrate (“NFC”) juices and dairy products, and it does not guarantee the necessary destruction of microorganisms that are heat resistant.